JP4895467B2 - Oxygen concentration method and oxygen concentration apparatus - Google Patents

Description

  The present invention relates to an oxygen concentrating method and an oxygen concentrating apparatus for producing concentrated oxygen by selectively adsorbing and separating nitrogen from a source gas containing nitrogen and oxygen such as air by the PSA method.

  A pressure swing adsorption method (hereinafter referred to as “a method of producing concentrated oxygen by selectively adsorbing and separating nitrogen from a source gas containing nitrogen and oxygen such as air and repeating adsorption / desorption using a molecular sieve such as zeolite as an adsorbent”. "PSA method" is industrially important and widely used in industries that use large amounts of oxygen, such as electric furnace steelmaking, pulp bleaching, fermentation, chemistry, water treatment, ozone production, melting furnace and other oxygen-enriched combustion. ing.

As a conventional technique for concentrating oxygen by the PSA method, air or the like is supplied into an adsorption tower filled with an adsorbent with an air compressor such as a low-pressure turbo blower to adsorb nitrogen to the adsorbent, There is one in which nitrogen adsorbed on the adsorbent is desorbed by reducing the pressure with a vacuum pump or the like (see, for example, Patent Document 1).
In addition, there is a configuration in which a plurality of adsorption devices, a vacuum pump, and a compressor are used as main elements (for example, see Patent Document 2).
JP-A-11-292506 (FIG. 1) Japanese Patent No. 2783358 (FIG. 1)

However, in the invention of Patent Document 1, since air or the like is supplied into the adsorption tower by an air compressor such as a low-pressure turbo blower, the electric power required for the operation of the air compressor is enormous and the operating cost increases. There was a problem such as.
In addition, the concentrated oxygen stored in the pressure equalizer is supplied (extruded) to a device located downstream via an extraction pipe by an air compressor such as a low pressure turbo blower. When the volume is small, the pressure of the concentrated oxygen in the pressure equalizer is affected by the pressure fluctuation in the adsorption tower. For this reason, the volume of the pressure equalizer is configured to be, for example, three times or more the volume of the adsorption tower, thereby reducing the pressure fluctuation of the concentrated oxygen in the pressure equalizer. Therefore, the volume of the pressure equalizer becomes very large, and there is a problem that the entire apparatus becomes large.
In addition, when such a fluid machine is used, it has the characteristic of increasing the pressure of the closed system, so a special control device or complicated operation is required to control the maximum pressure in the tower or to reduce the load during unloading. Since the noise and vibration are large, a great deal of cost is required for the countermeasures, and the problem is large in terms of equipment cost, operation cost and repair cost.

  On the other hand, in the invention of Patent Document 2, since the adsorber and the compressor are directly connected by a pipe, the influence of the compressor directly affects the adsorber, that is, the adsorption / desorption process (concentrated oxygen production process). Therefore, there has been a problem that the production efficiency cannot be improved.

The present invention has been made in view of the above-described circumstances, and can simplify driving operation more than before, reduce power consumption, and improve equipment, operation, and repair costs. It is an object of the present invention to provide an oxygen concentrating method and an oxygen concentrating apparatus that can perform the same.
Another object of the present invention is to improve the production efficiency of concentrated oxygen.

The present invention employs the following means in order to solve the above problems.
The invention described in claim 1 includes at least one adsorption tower filled with a molecular sieve such as zeolite that selectively adsorbs or desorbs nitrogen, and a pressure reducing means for reducing the pressure in the adsorption tower to an atmospheric pressure or lower. An oxygen concentrator comprising: a pressure equalizing tower for temporarily storing the produced concentrated oxygen; and a concentrated oxygen extracting means for extracting concentrated oxygen from the pressure equalizing tower to the outside of the system, the raw material containing oxygen and nitrogen A gas is naturally sucked into the adsorption tower whose pressure has been reduced to an atmospheric pressure or lower by the pressure reducing means, and the nitrogen in the raw material gas is adsorbed to the molecular sieve, and the concentrated oxygen is extracted by the concentrated oxygen extracting means. It is configured to be taken out.

According to such an oxygen concentrator, after the pressure in the adsorption tower is reduced to below atmospheric pressure (under negative pressure) by the decompression means, the raw material gas is naturally sucked into the adsorption tower and Nitrogen in the source gas is adsorbed on the stored molecular sieve, nitrogen is removed from the source gas, and concentrated oxygen is taken out of the system by the concentrated oxygen extracting means.
That is, the supply of the raw material gas into the adsorption tower is performed without using an air supply device such as a roots blower or a turbo blower.
Further, a pressure equalizing tower is disposed between at least one adsorption tower and the concentrated oxygen extraction means.

  According to a second aspect of the present invention, the concentrated oxygen extracting means is an oxygen compressor, and the concentrated oxygen is boosted to a predetermined pressure by the oxygen compressor and then sent out of the system. It is characterized by that.

  According to such an oxygen concentrator, concentrated oxygen that has been raised to a predetermined pressure higher than the atmospheric pressure by the oxygen compressor is discharged out of the system.

According to a third aspect of the present invention, there is provided at least one adsorption tower filled with a molecular sieve that selectively adsorbs or desorbs nitrogen, decompression means for reducing the pressure in the adsorption tower to an atmospheric pressure or less, and production. An oxygen concentration method for obtaining concentrated oxygen with an oxygen concentrator comprising a pressure equalizing tower for temporarily accumulating the concentrated oxygen and a concentrated oxygen extracting means for extracting the concentrated oxygen out of the system from the pressure equalizing tower, A step of reducing the pressure in the adsorption tower below the atmospheric pressure by the pressure reducing means, and a natural gas containing oxygen and nitrogen from the supply port of the adsorption tower into the adsorption tower reduced in pressure below the atmospheric pressure And adsorbing the nitrogen in the source gas to the molecular sieve, and extracting the concentrated oxygen from which the nitrogen has been removed from the source gas out of the system by a concentrated oxygen extracting means. , And it performs repeatedly the sequence of steps in a cycle of 50 seconds or less.

According to such an oxygen concentration method, after the pressure in the adsorption tower is reduced below the atmospheric pressure (under negative pressure) by the decompression means, the raw material gas is naturally sucked from the supply port of the adsorption tower and is adsorbed. Nitrogen in the raw material gas is adsorbed on the molecular sieve stored in the tower, nitrogen is removed from the raw material gas, and concentrated oxygen is taken out of the system by the concentrated oxygen extracting means.
That is, the supply of the raw material gas into the adsorption tower is performed without using an air supply device such as a roots blower or a turbo blower.
Further, a pressure equalizing tower is disposed between at least one adsorption tower and the concentrated oxygen extraction means.

  The invention according to claim 4 is characterized in that the concentrated oxygen extracting means is an oxygen compressor, and the concentrated oxygen is boosted to a predetermined pressure by the oxygen compressor and then sent out of the system.

  According to such an oxygen concentration method, the concentrated oxygen that has been increased to a predetermined pressure higher than the atmospheric pressure by the oxygen compressor is discharged out of the system.

According to the oxygen concentration method and oxygen concentration apparatus of the present invention, the following effects can be obtained.
Since the supply of the raw material gas into the adsorption tower is naturally sucked into the adsorption tower that has been depressurized (negative pressure state) without using an air supply device such as a Roots blower or a turbo blower. The consumption can be greatly reduced, and the operating cost can be greatly reduced.
Further, since the pressure equalizing tower is arranged between at least one adsorption tower and the concentrated oxygen extracting means, the influence on the adsorption / desorption process (concentrated oxygen production process) by the concentrated oxygen extracting means can be reduced. Manufacturing efficiency can be improved.

Furthermore, no special control devices or complicated operations are required to control the maximum pressure in the tower or to reduce the load during unloading, and the operation can be simplified, so noise and vibration can be reduced. Thus, the equipment cost and the repair cost can be reduced.
Furthermore, the produced concentrated oxygen is boosted to a predetermined pressure by an oxygen compressor and then sent out of the system (that is, a device located on the downstream side), so that the device located on the downstream side The concentrated oxygen can be stably supplied to the plant, and the operation of the entire plant can always be kept in a good state.

Hereinafter, an embodiment of an oxygen concentrator according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, an oxygen concentrator 100 according to the present invention includes, for example, two adsorption towers A and B, a suction filter 8 provided upstream of these adsorption towers A and B, and adsorption towers A and B. Pressure equalizing column C provided downstream of the pressure equalizing column C, an oxygen compressor (concentrated oxygen extracting means) 10 provided further downstream of the pressure equalizing column C, and an adsorbent contained in the adsorbing columns A and B The main component is a decompression pump (decompression means: vacuum pump) 9 for regenerating the above.

The adsorption towers A and B are of the same type and have supply ports 5A and 5B and outlets 7A and 7B, respectively, and nitrogen is selectively adsorbed or desorbed in the adsorption towers A and B, respectively. Adsorbents 11A and 11B made of zeolitic molecular sieves are packed.
The suction filter 8 removes impurities such as dust and dust from the raw material gas flowing into the adsorption towers A and B.
The pressure equalizing tower C is a container for temporarily storing the produced concentrated oxygen. For example, the outer shape of the pressure equalizing tower C is cylindrical or spherical. The volume of the pressure equalizing tower C is desirably 0.5 times or more and less than 3 times the volume of the adsorption towers A and B described above. By reducing the volume of the pressure equalizing tower C as compared with the conventional one, the overall size of the apparatus can be reduced.

The oxygen compressor 10 extracts (concentrates) the concentrated oxygen (product oxygen) stored in the pressure equalizing column C and increases the pressure, and supplies (sends) the concentrated oxygen to a device located on the downstream side.
The decompression pump 9 is used to discharge the gas remaining in the adsorption towers A and B into the atmosphere, or to desorb nitrogen gas adsorbed on the adsorbents 11A and 11B.

  The supply port 5A of the adsorption tower A and the supply port 5B of the adsorption tower B are connected to the outlet side of the suction filter 8 via an inlet pipe 20 provided with a valve 1A and a valve 1B, respectively. The supply port 5A of the adsorption tower A and the supply port 5B of the adsorption tower B are also connected to the suction side of the decompression pump 9 via a pipe 30 provided with a valve 4A and a valve 4B in the middle thereof.

On the other hand, the outlet 7A of the adsorption tower A and the outlet 7B of the adsorption tower B are respectively connected to the inflow side of the pressure equalizing tower C via an outlet pipe 12 provided with a valve 2A and a valve 2B in the middle thereof. . Further, the outlet 7A of the adsorption tower A and the outlet 7B of the adsorption tower B are connected by a pipe 40 having a pressure equalizing valve 3 and a purge valve 3P arranged in parallel on the way.
The outflow side of the pressure equalizing tower C and the suction side of the oxygen compressor 10 are connected by an extraction pipe 13, and a product oxygen pipe 14 is connected to the discharge side of the oxygen compressor 10. As a result, the concentrated oxygen that has passed through the extraction pipe 13 from the pressure equalizing tower C is boosted to a predetermined pressure by the oxygen compressor 10, and then passes through the product oxygen pipe 14 to the outside of the system (that is, a device located downstream). ).

Next, an oxygen concentration method for concentrating oxygen using the above-described oxygen concentrator 100 will be described with reference to FIGS.
FIG. 2 shows each step in this method, and elements unnecessary for explanation are omitted. FIG. 3 shows the pressure patterns of the adsorption towers A and B in each step. Here, the pressure is a gauge pressure.
In the oxygen concentration method according to the present invention, steps 1 to 6 described below are continuously operated as one cycle. This cycle will be described from the state in which the adsorption tower A finishes the regeneration and starts the adsorption, and the adsorption tower B finishes the adsorption and starts the regeneration.

  Step 1 (pressure equalization): The adsorption tower A that has finished regeneration (desorption of nitrogen) and the adsorption tower B that has finished adsorption are equalized by opening the pressure equalization valve 3. In the previous step (step 6), the adsorption tower A is in a depressurized state to near the lowest pressure (−about 63 kPa) by the regeneration process. Since the adsorption tower B has adsorbed nitrogen until just before, the adsorption tower pressure is close to the atmospheric pressure (0 kPa), and at this time, the gas flow through the pressure equalizing valve 3 flows from the adsorption tower B to the adsorption tower A. Direction. Further, since the adsorption tower A is in a depressurized state, by opening the valve 1A, the raw material gas is supplied (naturally) through the suction filter 8 through the supply port 5A. On the other hand, the vacuum pump 9 starts exhausting the adsorption tower B.

  Step 2 (Adsorption): When the pressure equalization step (Step 1) is completed, the adsorption tower A is still in a depressurized state. Therefore, by leaving the valve 1A open as it is, the adsorption tower A is subjected to natural suction. The pressure is increased to near atmospheric pressure and nitrogen is adsorbed. The outlet 7A of the adsorption tower A is in communication with the pressure equalizing tower C that temporarily stores product oxygen by opening the valve 2A. On the other hand, the pressure equalizing valve 3 leading to the outlet 7B of the adsorption tower B is closed, and the pressure is further reduced by the pressure reducing pump 9, and the adsorbed nitrogen gas and the like are desorbed.

  Step 3 (Washing): The pressure equalizing column C is extracted with product oxygen by the oxygen compressor 10, and the raw material gas is continuously supplied to the adsorption column A. While the adsorption tower B continues to exhaust from the supply port 5B by the decompression pump 9, on the other hand, the purge valve 3P is opened to introduce the concentrated oxygen from the adsorption tower A, and the residual nitrogen in the adsorption tower B is purged to a reduced pressure state. Drain while maintaining and regenerate the adsorbent.

Next, the adsorption tower A and the adsorption tower B are switched, and step 4 (pressure equalization), step 5 (adsorption), and step 6 (washing) are sequentially performed in the same manner as described above to form one cycle, and this cycle is repeated. Then, the concentrated oxygen is accumulated in the pressure equalizing column C, and the concentrated oxygen that has passed through the extraction pipe 13 is raised to a predetermined pressure by the oxygen compressor 10 and then sent out of the system.
Table 1 shows the time required for each step in the cycle and the opening / closing program.

  One of the objects of the oxygen concentration method and the oxygen concentration apparatus according to the present invention is to eliminate the need for a raw material gas supply device (air compressor) such as a low-pressure turbo blower or a roots blower, which has been conventionally required. This is because of the reduction of

[Experimental example A]
In order to actually confirm the performance of the oxygen concentrator according to the present invention, an experiment was performed using the oxygen concentrator shown in FIG. 4 (substantially the same as that disclosed in FIG. 1 of Patent Document 1 described above).
The oxygen concentrator shown in FIG. 4 is a so-called PSA oxygen production apparatus that uses a turbo blower to supply raw material air. Each of the adsorption tower A and the adsorption tower B shown in FIG. 4 has a cylindrical shape with a diameter of 950 mm and a height of 1500 mm, and the lower part of the tower is filled with activated alumina particles as a dehydrating agent, on which nitrogen gas separation is performed. As an adsorbent for use, a synthetic zeolite-based molecular sieve is packed. The pressure equalizing tower C is an empty tower that maintains a volume about 1.5 times that of the adsorption tower. The source gas supply air blower 15 is a low-pressure turbo blower having a discharge pressure of 20 kPa, and the decompression pump 9 is a wet two-stage roots blower. The oxygen compressor 10 is a roots blower having a discharge pressure of 30 kPa.

( Reference Example 1)
In order to obtain the same operation state as the oxygen concentrator according to the present invention, concentrated oxygen was produced by the steps and valve operations shown in FIG. 2 and Table 1 without using the raw material gas supply air blower 15 shown in FIG. . Air was used as the source gas.
In operation, the discharge valve 17 of the air blower was normally closed and the bypass valve 16 was normally opened to create the same state as the apparatus of FIG. Further, the operation time (seconds) and pressure change of the adsorption tower A and adsorption tower B in each step were also changed as shown in FIG. During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 63 kPa. The operation cycle was 60 seconds per cycle.
As a result of the operation in Reference Example 1, product oxygen of 48.1 Nm ³ / h could be obtained at an oxygen concentration of 90%. The power consumption per 1 Nm ^{3 of} product oxygen converted to 100% oxygen concentration was 0.44 kWh for the decompression pump and 0.04 kWh for the oxygen compressor, for a total of 0.48 kWh.

(Comparative Example 1)
In order to compare the performance of the oxygen concentrator according to the present invention and the conventional oxygen concentrator, the oxygen concentrator shown in FIG. 4 was used to produce concentrated oxygen by the steps and valve operations shown in FIG. 5 and Table 2 below. went. In this case, the source gas was supplied using the source gas supply air blower 15.

The operation time (seconds) and pressure change of the adsorption tower A and adsorption tower B in each step were also changed as shown in FIG. During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was about 21 kPa, and the minimum pressure (minimum desorption pressure) was -about 61 kPa. The operation cycle was 64 seconds per cycle.
As a result of the operation in Comparative Example 1, product oxygen of 49.1 Nm ³ / h was obtained at an oxygen concentration of 90%. The power consumption per 1 Nm ^{3 of} product oxygen converted to 100% oxygen concentration was 0.37 kWh for the decompression pump, 0.03 kWh for the oxygen compressor, and 0.23 kWh for the air blower, totaling 0.63 kWh.

  As described above, since the oxygen concentration method according to the present invention was performed using the conventional equipment as it was, the suction pressure of the vacuum pump could not be lowered, and the product oxygen amount was slightly reduced as compared with the conventional one. Was reduced by about 24%.

[Experiment B]
In order to actually confirm the performance of the oxygen concentrator according to the present invention, the oxygen concentrator shown in FIG. 4 (however, the adsorption tower A and the adsorption tower B are both cylindrical with a diameter of 30 mm and a height of 1000 mm). 7 and the oxygen concentrator shown in FIG. 7 (apparatus substantially the same as that disclosed in FIG. 1 of Patent Document 2 described above, that is, an apparatus excluding the pressure equalizing tower C from the configuration of FIG. 1 of the present application). went.
The oxygen concentrator shown in FIG. 7 is a so-called PSA oxygen production apparatus. Each of the adsorption tower A and the adsorption tower B shown in FIG. 7 has a cylindrical shape with a diameter of 30 mm and a height of 1000 mm. The lower part of the tower is filled with activated alumina particles as a dehydrating agent, on which nitrogen gas separation is performed. As an adsorbent for use, a synthetic zeolite-based molecular sieve is packed. The pressure equalizing tower C is an empty tower that maintains a volume about 1.5 times that of the adsorption tower. The decompression pump 9 is a wet two-stage roots blower, and the oxygen compressor 10 is a roots blower having a discharge pressure of 30 kPa.

( Reference Example 2)
In order to obtain the same operation state as the oxygen concentrator according to the present invention, the concentrated oxygen can be produced by the steps and valve operations shown in FIG. 2 and the following Table 3 without using the raw material gas supply air blower 15 shown in FIG. went. Air was used as the source gas.
In operation, the discharge valve 17 of the air blower was normally closed and the bypass valve 16 was normally opened to create the same state as the apparatus of FIG. Further, the operation time (seconds) and pressure change of the adsorption tower A and adsorption tower B in each step were also changed as shown in FIG. During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operation cycle was 60 seconds per cycle.

(Example 3)
In order to obtain the same operation state as the oxygen concentrator according to the present invention, concentrated oxygen was produced by the steps and valve operations shown in FIG. 2 and Table 3 without using the raw material gas supply air blower 15 shown in FIG. . Air was used as the source gas.
In operation, the discharge valve 17 of the air blower was normally closed and the bypass valve 16 was normally opened to create the same state as the apparatus of FIG. Further, the operation time (seconds) and pressure change of the adsorption tower A and adsorption tower B in each step were also changed as shown in FIG. During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operation cycle was 50 seconds per cycle.

Example 4
In order to obtain the same operation state as the oxygen concentrator according to the present invention, concentrated oxygen was produced by the steps and valve operations shown in FIG. 2 and Table 3 without using the raw material gas supply air blower 15 shown in FIG. . Air was used as the source gas.
In operation, the discharge valve 17 of the air blower was normally closed and the bypass valve 16 was normally opened to create the same state as the apparatus of FIG. Further, the operation time (seconds) and pressure change of the adsorption tower A and adsorption tower B in each step were also changed as shown in FIG. During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operation cycle was 40 seconds per cycle.

(Comparative Example 2)
In order to compare the performance of the oxygen concentrator according to the present invention and the conventional oxygen concentrator, the oxygen concentrator shown in FIG. 7 is used to produce concentrated oxygen by the steps and valve operations shown in FIG. 8 and Table 4 below. went.
During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operation cycle was 50 seconds per cycle.

(Comparative Example 3)
In order to compare the performance of the oxygen concentrator according to the present invention and the conventional oxygen concentrator, concentrated oxygen was produced by the steps and valve operations shown in FIG. 8 and Table 4 using the oxygen concentrator shown in FIG. .
During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operation cycle was 42 seconds per cycle.

(Comparative Example 4)
In order to compare the performance of the oxygen concentrator according to the present invention and the conventional oxygen concentrator, concentrated oxygen was produced by the steps and valve operations shown in FIG. 8 and Table 4 using the oxygen concentrator shown in FIG. .
During the operation period, the maximum pressure (maximum adsorption pressure) of the adsorption tower was −about 1 kPa, and the minimum pressure (minimum desorption pressure) was −about 73 kPa. The operating cycle was 36 seconds per cycle.

Table 5 below shows the operation results in Reference Example 2 , Examples 3 and 4, and Comparative Examples 2 to 4 described above.

From Table 5, the oxygen concentrator equipped with the pressure equalizing tower C ( Reference Example 2 , Examples 3 and 4) is more than the oxygen concentrating apparatus not equipped with the pressure equalizing tower C (Comparative Examples 2 to 4). It can be seen that the recovery rate and the oxygen production amount are extremely high.
Here, the recovery rate (%) is that of the so-called efficiency, and shows how it was possible to take out how much oxygen of the oxygen in the feed by weight.
The oxygen production amount is the amount of oxygen produced by 1 kg of adsorbent per day.

  In the embodiment described above, an experiment was conducted on an oxygen concentrator having two adsorption towers. However, the present invention is not limited to this, and the oxygen concentrator having one or three or more adsorption towers is used. It can also be applied to.

It is a schematic block diagram which shows one Embodiment of the oxygen concentration apparatus by this invention. It is a figure which shows one Embodiment of the oxygen concentration method by this invention performed using the oxygen concentration apparatus shown in FIG. 1, Comprising: It is a figure for demonstrating the flow state for every step. It is a graph which shows the relationship between the operation time and operating pressure in embodiment shown in FIG. It is a schematic block diagram which shows one specific example of the conventional oxygen concentration apparatus. It is a figure which shows one specific example of the oxygen concentration method performed using the oxygen concentration apparatus shown in FIG. 4, Comprising: It is a figure for demonstrating the flow state for every step. It is a graph which shows the relationship between the operation time in one specific example shown in FIG. 5, and an operating pressure. It is a schematic block diagram which shows the other specific example of the conventional oxygen concentration apparatus. It is a figure which shows one specific example of the oxygen concentration method performed using the oxygen concentration apparatus shown in FIG. 7, Comprising: It is a figure for demonstrating the flow state for every step.

Explanation of symbols

1A valve 1B valve 2A valve 2B valve 3 pressure equalizing valve 3P purge valve 4A valve 4B valve 5A supply port 5B supply port 7A outlet 7B outlet 8 suction filter 9 pressure reduction pump (pressure reduction means)
10 Oxygen compressor (means for extracting concentrated oxygen)
11A adsorbent (molecular sieve)
11B adsorbent (molecular sieve)
12 outlet pipe 13 extraction pipe 14 product oxygen pipe 15 air blower for raw material gas supply 16 bypass valve 17 discharge valve 100 oxygen concentrator A adsorption tower B adsorption tower C pressure equalization tower

Claims (4)

At least one adsorption tower filled with a molecular sieve such as zeolite that selectively adsorbs or desorbs nitrogen, pressure reducing means for reducing the pressure in the adsorption tower below atmospheric pressure, and temporarily storing the produced concentrated oxygen An oxygen concentrator comprising: a pressure equalizing tower to be stored; and concentrated oxygen extracting means for extracting concentrated oxygen from the pressure equalizing tower outside the system,
A raw material gas containing oxygen and nitrogen is naturally sucked into the adsorption tower whose pressure has been reduced to below atmospheric pressure by the pressure reducing means, and the nitrogen in the raw material gas is adsorbed on the molecular sieve, thereby extracting the concentrated oxygen. An oxygen concentrator configured to extract concentrated oxygen out of the system by means. Together with the concentrated oxygen extraction means is oxygen compressor, said enriched oxygen after being boosted to a predetermined pressure by the oxygen compressor, to claim 1, characterized in that is adapted to be fed out of the system The oxygen concentrator described. At least one adsorption tower filled with a molecular sieve that selectively adsorbs or desorbs nitrogen, pressure reducing means for reducing the pressure in the adsorption tower below atmospheric pressure, and temporarily storing the concentrated oxygen produced. An oxygen concentrating method for obtaining concentrated oxygen by an oxygen concentrating device comprising a pressure equalizing tower and a concentrated oxygen extracting means for extracting concentrated oxygen from the pressure equalizing tower out of the system,
Reducing the pressure in the adsorption tower to atmospheric pressure or less by the decompression means;
A step of allowing the raw material gas containing oxygen and nitrogen to be naturally sucked from the supply port of the adsorption tower into the adsorption tower whose pressure is reduced to an atmospheric pressure or lower, and the molecular sieve to adsorb the nitrogen in the raw material gas;
A step of extracting concentrated oxygen from which the nitrogen has been removed from the raw material gas by a concentrated oxygen extracting means ;
An oxygen concentration method, wherein the series of steps are repeated in one cycle of 50 seconds or less . The oxygen concentration method according to claim 3 , wherein the concentrated oxygen extraction means is an oxygen compressor, and the concentrated oxygen is boosted to a predetermined pressure by the oxygen compressor and then sent out of the system.

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